kafka.server.LogOffsetMetadata.scala Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package kafka.server
import kafka.log.Log
import org.apache.kafka.common.KafkaException
object LogOffsetMetadata {
val UnknownOffsetMetadata = LogOffsetMetadata(-1, 0, 0)
val UnknownFilePosition = -1
class OffsetOrdering extends Ordering[LogOffsetMetadata] {
override def compare(x: LogOffsetMetadata, y: LogOffsetMetadata): Int = {
x.offsetDiff(y).toInt
}
}
}
/*
* A log offset structure, including:
* 1. the message offset
* 2. the base message offset of the located segment
* 3. the physical position on the located segment
*/
case class LogOffsetMetadata(messageOffset: Long,
segmentBaseOffset: Long = Log.UnknownOffset,
relativePositionInSegment: Int = LogOffsetMetadata.UnknownFilePosition) {
// check if this offset is already on an older segment compared with the given offset
def onOlderSegment(that: LogOffsetMetadata): Boolean = {
if (messageOffsetOnly)
throw new KafkaException(s"$this cannot compare its segment info with $that since it only has message offset info")
this.segmentBaseOffset < that.segmentBaseOffset
}
// check if this offset is on the same segment with the given offset
def onSameSegment(that: LogOffsetMetadata): Boolean = {
if (messageOffsetOnly)
throw new KafkaException(s"$this cannot compare its segment info with $that since it only has message offset info")
this.segmentBaseOffset == that.segmentBaseOffset
}
// compute the number of messages between this offset to the given offset
def offsetDiff(that: LogOffsetMetadata): Long = {
this.messageOffset - that.messageOffset
}
// compute the number of bytes between this offset to the given offset
// if they are on the same segment and this offset precedes the given offset
def positionDiff(that: LogOffsetMetadata): Int = {
if(!onSameSegment(that))
throw new KafkaException(s"$this cannot compare its segment position with $that since they are not on the same segment")
if(messageOffsetOnly)
throw new KafkaException(s"$this cannot compare its segment position with $that since it only has message offset info")
this.relativePositionInSegment - that.relativePositionInSegment
}
// decide if the offset metadata only contains message offset info
def messageOffsetOnly: Boolean = {
segmentBaseOffset == Log.UnknownOffset && relativePositionInSegment == LogOffsetMetadata.UnknownFilePosition
}
override def toString = s"(offset=$messageOffset segment=[$segmentBaseOffset:$relativePositionInSegment])"
}